EP0034994A1 - Composite product of a tubular envelope and a core of compacted pulverulent material and its manufacturing method - Google Patents

Abstract

The invention relates more generally to a composite product with a metallic tubular casing, the core of which is a pulverulent or granular material, capable of being easily wound up, then unwound and erected. According to the invention, the pulverulent material is located inside the envelope in the compacted state and moreover the section of the product has at least two flattened zones opposite one another. The invention also relates to the method for producing this product and its application to the treatment of molten metal baths. This product is mainly used for refining, deoxidation or calming of molten metal baths, in particular in the case of steels.

Description

The invention relates more generally, a composite product with a tubular casing, comprising a metallic casing and a core made of a pulverulent or granular material which adheres to the casing, able to be easily rolled up then unrolled and erected.

The invention also relates to the method of manufacturing this composite product.

Finally, the invention also relates to a method of treating molten metal baths using this composite product.

The introduction into molten metal baths of substances intended to refine, deoxidize, degas them, calm them and / or modify their composition, is common practice in metallurgy.

Many methods or devices have been developed to improve the efficiency of introduction of these substances and also the efficiency and reproducibility of the results.

Thus, US Patent 2,705,196 describes the addition, in steel or liquid iron, of aluminum, silicon, silico-calcium or other materials as deoxidizers. In order to avoid oxidation on the surface of the bath of these additives, these are wrapped in an envelope which may for example be made of mild steel and which is immersed in the bath by any suitable method.

FR 2,269,581 also describes a method of introducing an aluminum wire or another metal or reducing alloy into liquid steel to deoxidize or calm it in the case of a casting installation keep on going. To avoid surface oxidation of the wire, it is coated with a thin steel casing which protects it from oxidation before entering the metal bath. This allows the steel to be continuously deoxidized by introducing aluminum wire coated with its envelope at a suitable speed, directly into the continuous casting mold for the duration of this casting.

The sheathing of the reducing metal wire is carried out in a very simple way by wrapping it in a thin metallic ribbon which is plated on the wire by passing the assembly through dies of diameter decreasing. The ribbon is thus wound around the wire with covering and drawing, the wire playing the role of mandrel. A composite product of circular section is thus obtained which can be wound into a reel and which, at the time of use, will be unwound by means of a suitable unwinding and driving device, which will allow it to be introduced at the desired speed. in the metal bath to be treated.

Finally, US Patent 3,915,693 describes a composite product which comprises a metallic envelope and a core constituted by a granular material, which is used in particular for deoxidation treatments, grain refining, or the like, in continuous casting. metals such as aluminum or steel.

The product is produced either by filling a preexisting tube with the granular material, or by enclosing the granular material in a metallic envelope formed continuously from a strip. In both cases, a gradual reduction in diameter is carried out on the filled tube by different methods such as rolling, hammering or drawing, which make it possible to increase the length of the tube while reducing its diameter and thickness. . The composite product obtained is always of circular section.

Thus, for example, this patent describes a tube filled with granular material whose outside diameter is 1 inch (25.4 mm) which is reduced to a final diameter of 3/8 inch (9.5 mm). During the reduction operation, the length of this tube is increased from 246 feet (approximately 75m) to 1755 feet (approximately 535m), ie an aspect ratio of approximately 7.1. It can be seen that, under these conditions, the initial thickness of the wall of the tube is divided by approximately 2.7.

The tests carried out with a view to applying the teaching of these patents to the production of tubular composite products comprising a core of pulverulent or granular material and an envelope produced from a metal strip or ribbon, have shown that It is difficult to carry out a reduction by stretching after closing the envelope. Indeed, in the absence of a ductile core which can serve as a support for this envelope and deform at the same time as it, this envelope tends to elongate irregularly and to rupture, and also to take an external shape. difficult to control. In addition, tests have shown that it is difficult to keep the quality of a composite product comprising a thin steel envelope of circular section and a core of a pulverulent material, as regards in particular the shape of this envelope and the cohesion of the core, during its implementation which involves winding on a drum or reel, then unwinding followed by dressing.

It has also been found that, if the pulverulent material is not compacted inside the envelope, this material does not adhere and tends to move inside this envelope during handling, and therefore to be distributed heterogeneously, which disrupts use.

Ways have been sought to resolve these difficulties, that is to say to produce a composite product with a tubular casing comprising a pulverulent or granular porous core which adheres to the casing and remains consistent despite the manipulations, this product being capable of winding on reel or drum and unwinding.

The object of the invention is a composite product with a tubular casing which comprises a metal casing, closed by stapling and possibly crimping parallel to its axis, inside which is housed a pulverulent or granular material.

The section of this product comprises at least two flattened parallel zones arranged opposite one another.

This section can for example be square or rectangular or even have the shape of a flattened oval. Particularly favorable results are obtained in the case of sections in which the ratio between the largest axis and the smallest axis, the latter measuring the distance between two parallel flattened zones arranged opposite one another, is at least 1.1.

Another object of the invention is a process for producing this composite product with a tubular envelope.

According to this method, one starts from a tubular casing of substantially circular section, obtained by any method, inside which has been accommodated, by any method also, a pulverulent or granular non-packed material.

This starting product is subjected to a deformation of its section, with a substantially constant perimeter and without significant elongation in the direction length so as to compact the pulverulent or granular material without significant displacement relative to the envelope. In addition, this deformation is carried out so as to obtain two flattened parallel zones opposite one another.

• a) profilage d'une bande métallique pour lui donner une forme de gouttière,
• b) introduction à l'intérieur de cette gouttière d'une quantité déterminée de matière pulvérulente ou granulaire,
• c) profilage des deux bords de cette gouttière puis rapprochement de ces deux bords l'un contre l'autre en enfermant la matière pulvérulente ou granulaire introduite,
• d) agrafage des deux bords l'un à l'autre, puis éventuellement sertissage, de façon à constituer un produit composite de section sensiblement circulaire,
• e) déformation de la section du produit composite à périmètre sensiblement constant et sans allongement notable, de façon à compacter la matière pulvérulente et à obtenir au moins deux zones aplaties, parallèles, en face l'une de l'autre.

Preferably, the product according to the invention is produced in the following way:

• a) profiling a metal strip to give it a gutter shape,
• b) introduction into the interior of this gutter of a determined quantity of pulverulent or granular material,
• c) profiling of the two edges of this gutter then bringing these two edges together against each other by enclosing the pulverulent or granular material introduced,
• d) stapling of the two edges to each other, then possibly crimping, so as to constitute a composite product of substantially circular section,
• e) deformation of the section of the composite product at a substantially constant perimeter and without significant elongation, so as to compact the pulverulent material and to obtain at least two flattened, parallel zones, facing one another.

Thus, the compacting of the pulverulent material carried out in "e" above is carried out by simple reduction of section without elongation and without modifying the thickness of the envelope, leaving the material constituting the core in the porous state. . This avoids hardening of the metal shell of the composite product, and facilitates the subsequent use of the finished product.

Finally, the invention also relates to a method of treating molten metal baths with pulverulent or granular materials in the compacted state constituting the core of the composite product with tubular envelope which constitutes the first object of the invention.

According to this method, the composite product with a tubular envelope previously wound on a drum or a reel is unwound, then erected, then introduced into the metal bath to be treated at a speed and for a time which are adjusted according to the quantities to be introduced and the duration of the metallurgical process.

The detailed description and the nonlimiting example which follow, allow, with the help of the appended figures whose list is given below, to fully understand the invention.

• FIG. 1 generally illustrates a forming chain implementing the method of the invention.
• Figures 1a to 1f illustrate the shape of the profile at different points in Figure 1.
• FIG. 2 illustrates a variant of the forming line according to the invention.
• Figures 3 to 5 illustrate different forms of composite products with a tubular casing manufactured according to the invention.
• FIG. 6 illustrates how the composite product with a tubular envelope according to the invention can be stored, wound on a drum or a reel.

Although the invention may be applied in general, the detailed description below relates more particularly to the refining, deoxidation, degassing, calming of molten metal baths, and / or modification or adjustment of the composition by means of a composite product, the envelope of which is a strip of a metal compatible with the bath, such as: a steel, aluminum, copper, or another metal or alloy. The core consists of the powdery or granular treatment material.

In FIG. 1, a roller (10) delivers, along the arrow, a metal strip (101) of steel for example, to a continuous cold forming line, starting with a first series (11) of forming rollers such that (110) to (115). At point a (Figure la), one begins to deform the strip giving it a hollow profile (102). At point b (last rollers 115 and FIG. 1b), the strip has received a semi-closed cross section in the form of a gutter, its two edges (116) and (117) being suitably shaped so that one can later be attached to the other. At point c (FIG. 1c), a dispensing nozzle (120) fills in passing the gutter (103) with the pulverulent treatment material (105). This filling can be quantified in itself, by regulating the flow rate of pulverulent material (pressure applied for example). Preferably, we then adjusts the dosage of the pulverulent material, for example by equalizing its level by means of a scraper (125 figure 1d). Advantageously, the latter also performs wiping of the edges (116) and (117), on the internal side.

Then, the forming line comprises a second series (13) of forming rollers, such as (130) to (135). These bring the edges (116) and (117) towards each other, staple them to each other at point e (figure le), then preferably crimp the connection thus formed by crushing the joint of the two edges (figure If).

Then, the forming chain is completed by a third series (14) of rollers, such as (140) to (145) which deform the envelope, without appreciable axial elongation, and cause a reduction in section at constant perimeter, giving the product a section having at least two flattened parallel zones opposite one another. Preferably, the reduction in section carried out is of the order of at least 15%. This produces a compacting of the pulverulent material on site, which gives it good cohesion as well as excellent support inside the envelope which encloses it. This gives a limited compression of the pulverulent or granular material which remains porous. The closed gutter (Figure If) being substantially circular, one easily obtains according to the invention, a flattened profile close to a rectangle (106 Figure 3), a flattened oval (107 Figure 4) or a rectangle with short semicircular sides (108 figure 5). The crimped seal is preferably folded down as shown in the figures

3 to 5, on a large side of the rectangle or oval at one of the two flattened areas.

The composite product with a tubular envelope thus obtained can be easily wound on a drum (150) as seen in FIG. 6, in the case of a product of almost rectangular section, by a guide system for example of the type with cam in the heart or by any other means which ensures suitable cutting. In some cases, especially for large thicknesses of the envelope, the introduction and metering of the pulverulent material may be carried out as illustrated in FIG. 2: a hollow mandrel (200) is supported by a bar (201) also hollow , to be introduced into the gutter before it is closed, produced in (210) by rollers not shown. The pulverulent or granular material is pushed inside the mandrel holder bar (201) and the hollow mandrel (200) to be introduced into the gutter at the level of the head of the mandrel (205). Enlarged to the suitable shape, it serves at the same time as a support to ensure the crimping of the edges (116) and (117), as illustrated in FIG. Then, the material is compacted according to the invention using the third series (14) of forming rollers (Figure 1).

Of course, the filling can be carried out as a variant by other injection means with or without gas pressure, depending on the characteristics of the pulverulent or granular material and the geometric shape of the envelope.

The application to the treatment of molten metal baths is carried out as follows: the quantity of product required is known; the drum (150) is brought above the bath, and the suitable length of the composite product according to the invention is unrolled therein in a short time, cut by suitable means at the end of the process. This means is particularly suitable for steel pockets or continuous casting distributors.

The metal casing is generally produced from a folded and crimped band, made of the same base metal as the liquid metal. This envelope is therefore in this sense non-reactive with respect to the metal bath.

The envelope can also be used as actual filler metal, for example an aluminum envelope for introduction into a steel bath.

• - des réducteurs tels que le calcium, le magnésium, le sodium, le bore, le titane, le zirconium, les terres-rares, ou encore d'autres éléments ou composés réducteurs,
• - des éléments adjuvants destinés à modifier les propriétés du métal, ou encore des éléments d'addition divers tels que le plomb, le bismuth, le sélénium, le tellure, ou le soufre,
• - des éléments d'addition destinés à ajuster la composition du bain métallique avec précision analytique accrue tels que C, Si, Mn, Ni, Cr, Mo,
• - tous alliages contenant les éléments ci-dessus associés à des métaux de base comme le fer, le silicium, l'aluminium, le cuivre, notamment. La matière peut également comporter en tout ou en partie, des laitiers en poudre, dont la composition correspond à celle des laitiers généralement utilisés dans les réactions métallurgiques d'élaboration ou d'affinage du métal liquide traité, tels qu'un mélange de chrome, d'alumine et de spath fluor.

The pulverulent or granular material which constitutes the core can be based on metals or alloys, slag or a mixture of these products. This material can in particular comprise reactive substances for refining, deoxidizing, degassing or calming the molten metal bath, or for modifying the nature of the inclusions, or even for playing the role of adjuvants. We can cite in particular:

• - reducing agents such as calcium, magnesium, sodium, boron, titanium, zirconium, rare earths, or other reducing elements or compounds,
• - additive elements intended to modify the properties of the metal, or also various addition elements such as lead, bismuth, selenium, tellurium, or sulfur,
• addition elements intended to adjust the composition of the metal bath with increased analytical precision such as C, Si, Mn, Ni, Cr, Mo,
• - all alloys containing the above elements associated with base metals such as iron, silicon, aluminum, copper, in particular. The material may also comprise, in whole or in part, powdered slag, the composition of which corresponds to that of slag generally used in metallurgical reactions for preparing or refining the treated liquid metal, such as a mixture of chromium, alumina and fluorspar.

The nonlimiting example below describes an embodiment of the invention.

Example 1:

A composite product with a tubular envelope was produced by the above method from a steel strip 0.4 mm thick and 36.4 mm wide. After having formed it into a gutter, a pulverulent material based on Si Ca containing 30% of Ca was introduced inside. It was then rolled, stapled, and crimped the strip so as to obtain a 10 mm tube. outside diameter filled with powdery material.

This tube was then crushed so as to obtain a practically rectangular cross section with rounded angles and measuring 11 x 6 mm. This final deformation was carried out cold, without appreciable elongation and resulted in a reduction of the internal section of approximately 16Z. This resulted in effective compaction of the pulverulent material and also a tightening of the envelope on this compacted material which guarantees that the pulverulent or granular material is kept in place during subsequent manipulations.

The composite product was wound by cutting on a coil of 600 mm in diameter. We thus obtained a filling density of the coil 20 to 25% higher than it would be with a round product. The excellent mechanical strength of the composite product was observed during this winding as well as during the subsequent unwinding during use. The composite product penetrates well into the heart of a bath of molten steel. Remaining both porous and compressed, the pulverulent or granular material reacts with the liquid steel under optimal conditions of efficiency and yield.

Of course, the present invention is not limited to the embodiment described, and extends to any variant in accordance with its spirit. It is in particular susceptible of other applications, for example in the case of steel welding electrodes internally containing their flux, for bath welding.

Claims (16)

1. Composite product with a long tubular casing capable of being rolled up then unrolled and erected, comprising a metallic casing (103) and a core (105) made of a pulverulent or granular material, the casing being closed by stapling along a generator, characterized in that the pulverulent or granular material is compacted inside the envelope and in that the section of the product has at least two flattened parallel zones opposite one another (106-107 -108). 2. Product according to claim 1, characterized in that its section is substantially square. 3. Product according to claim 1, characterized in that its section is substantially rectangular (106-108). 4. Product according to claim 1, characterized in that its section is a flattened oval (107). 5. Product according to one of claims 1, 3 or 4, characterized in that in the plane of its section the ratio between the largest axis and the smallest axis is at least 1.1. 6. Product according to one of claims 1 to 5, characterized in that its envelope is made of a ferrous or non-ferrous metal. 7. Product according to one of claims 1 to 6, characterized in that its core is a pulverulent or granular compacted material based on pure metals and / or alloys and or dairy. 8. Product according to one of claims 1 to 7, characterized in that the pulverulent or granular material contains one or more reactive elements such as Ca, Ba, Mg, Na, B, Ti, Zr, and / or metals of the rare earths and / or other addition elements such as Pb, Bi, Se, Te, S. 9. Product according to claim 8, characterized in that it additionally contains at least one alloy based on a metal from the group comprising 10. A method of manufacturing a composite product with a tubular casing, characterized in that a tubular casing of substantially circular section is prepared by any method, inside which is housed a powdery or granular material which is not compacted, then this product is subjected to a deformation of its section with a substantially constant perimeter and without significant elongation in the lengthwise direction, so as to compact the pulverulent or granular material which constitutes the core, without significant displacement relative to the envelope, and in that this deformation is carried out so as to obtain two flattened parallel zones opposite one another. 11. Method according to claim 10, characterized in that it comprises the following steps: a) a metal strip is profiled to give it the shape of a gutter, b) a determined quantity of pulverulent or granular material is introduced into this gutter, c) the two edges of the gutter are profiled and then these two edges are brought together against one another by enclosing the material introduced, d) the two edges are stapled together so as to constitute a composite product with a tubular casing of substantially circular section, e) the section of the composite tubular product is deformed at a substantially constant perimeter without appreciable elongation, this deformation being carried out so as to obtain two parallel flattened zones opposite one another. 12. Method according to claim I1, characterized in that after filling the gutter with powdery or granular material, the level thereof is equalized by means of a scraper. 13. Method according to one of claims Il or 12, characterized in that after stapling of the two edges, a crimping is carried out. 14. Method according to one of claims 10 to 13, characterized in that the deformation of the product which is carried out from a substantially circular initial section, causes a reduction in section of about 15% or more. 15. Method of treatment of a molten metal bath with a pulverulent or granular material which constitutes the core of a composite product according to one of claims 1 to 9, characterized in that the composite product previously wound on a drum is unwound , then erected, then introduced into this metal bath at a speed and for a time which are adjusted according to the quantities to be introduced and the duration of the metallurgical process. 16. Treatment method according to claim 15, characterized in that the molten metal bath is steel, and the envelope of the composite product is aluminum.

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